1. Field of the Invention
This invention relates to a molded plastic binding for sheets with holes. The holes are preferably of the same size and pattern as those marketed worldwide by General Binding Corporation (GBC) and its competitors for several decades.
2. Description of the Related Art
One common means that has been used to bind variable thicknesses of paper is a two-element metal binder comprising a first linear element, the ends of which extend upward through hoes in the material to be bound, through holes in a flat upper second element, and toward each other on the top of the sheets to be bound. Two sliding enclosures hold the ends of the first element to the second element. Such a binding provides an easily releasable binding for adjustment of the number of bound sheets, and rebinding of the new sheets.
Another binding system, GBC binding systems, uses flat, plastic blanks resembling a comb with fingers curled into its binding strip. The bindings are typically used with sheets having 19 holes, each measuring approximately 0.125".times.0.300" and located on 0.5625" centers adjacent to one long edge of 81/2".times.11" paper sheets. Larger sheets with more holes are generally used outside the United States. Users insert the binding into a machine where it is uncoiled slightly so that a stack of sheets bearing holes can be engaged with the comb fingers. When the coiled fingers are restored to their original position, the now bound stack of sheets is free to pivot upon the coiled binding. This book will lie flat and open to a selected page or fold back upon itself for convenient handling. Such bound books can be unbound to add, delete, or change page sequence.
As GBC plastic bindings proliferated throughout the world, the need arose to bind thicker, heavier books with greater security. In the field of binding, the words "secure" and "security" refer to the ability of a binding to hold its contents intact without failure in the ordinary or abnormal use of the bound product. This need for security led to GBC's development of its now-expired patented "SURELOX" binding which employed arrowhead-like tips on two or more fingers that were inserted into notched holes in the binding strip (Lane, U.S. Pat. No. 2,910,068). The disclosure of this patent and all other patents and patent applications cited herein is incorporated herein by reference. Books bound in this manner resist abuse but are time-consuming to assemble. Demands for more security continued and bookbinders began to cement the finger tips of bindings to binding strips to hold them in place. While this process seemed to work well, the adhesives then available embrittled the plastic over time and caused premature failures of bound books.
In the late 1960's the Velo-bind Corporation (Sunnyvale, Calif.) began marketing a binding system having the purpose of binding paper sheets securely. The Velo-bind system, described in Abildgaard (U.S. Pat. No. 3,596,929, Reissue No. 28,202 and others) binds sheets with 0.125" diameter holes on 1" centers adjacent to the long edge of 81/2".times.11" sheets. Sheets are bound by inserting an eleven-fingered plastic binding strip into coinciding holes of piled sheets. The straight fingers protrude through the stack so that a second, flat binding strip with recessed holes will mate with the protruding fingers. The stack is compressed and the portions of each finger beyond the binding strip are removed by hot-shearing. This smears the near-molten plastic into recessed holes and around the finger stubs thus producing a type of flush rivet.
When books are bound with a Velo-bind binding, they are considered permanently bound since they are not intended to be unbound to delete, add, or change page sequences. If such a book is unbound for any reason, a brand new binding must be used to rebind the book. Books bound with a Velo-bind binding, when opened, do not lie flat and cannot assume a back-to-back mode.
Generally speaking, the marketplace has accepted Velo-bind's bindings despite the fact that the bound books do not lie flat, the covers cannot be put back-to-back, and it is not possible to "unbind" a bound book to delete, add or change page sequences without destruction of the original binding. Velo-bind users also encounter occasional catastrophic failure of their rivet heads when thick, heavy bound books are dropped on the floor, bumped or opened abruptly after prolonged exposure to cold environments. Despite these negative aspects, thin books bound with the Velo-bind system have the appearance and reputation of security.
A number of patents disclose plastic binding strips having longitudinally spaced studs which can be bent over at a 90.degree. angle. For example, the studs of Hymmen (U.S. Pat. No. 4,625,996) are serrated and fit into serrated grooves on a second binding strip. Although such bindings may be used on a variety of thicknesses of bound paper, the discrete nature of the serrations means that for some sizes of bound books, the binding may be too tight or too loose when the serrated strip is hooked into the best-fitting position i the serrated grooves.
The patents of Abildgaard (U.S. Pat. Nos. 4,674,906 and 4,685,700) disclose strips having round studs bendable at 90 degrees into grooves in shaped overhangs in a second strip. The studs are smooth and round and are detachably secured in the grooves, and may possibly be dislodged accidentally by a sharp blow or twisting of the book. They do not have a structural mechanism for securely locking the studs in the overhangs.
Another invention by the inventor herein, described in pending patent application U.S. application Ser. No. 256,462, filed Oct. 12, 1988, issued as U.S. Pat. No. 4,997,208 on Mar. 5, 1991, also discloses a security binder for positively and permanently securing a plurality of sheets. The binding strip elements are provided with lateral projecting members having angled projections permitting entry of the projecting members into spaced apertures but preventing removal from the apertures.
From the foregoing it is clear that there is a need and market for secure binding systems which are held together firmly. It is therefore an object of this invention to provide a binding system which has the ability to lock to hold contents intact. It is a further object of the invention to provide a binding system which may be made to fit standard rectangular-punched (GBC) holes on paper sheets.
Other objects and advantages will be more fully apparent from the following disclosure and appended claims.